1. Field of the Invention
The present invention generally relates to gas turbine engines and, more particularly, to a system and a method for monitoring the operational condition of a gas turbine engine. The invention also relates, more generally, to a method for monitoring and detecting changes within a system.
2. Description of the Prior Art
Over time, fuel nozzles of gas turbine engines are known to develop deposits, herein referred to as coke, in the fuel passage proximate the engine combustor. Streaking fuel nozzles and/or blocked fuel nozzles due to coking can result in premature hot end distress (turbine blades creeping, blade ruptures, and thermal disparity). Sometimes, over-temperatured vanes can fracture resulting in surge (among other things). As a result, fuel injection nozzles are periodically removed from the engine and subject to a cleaning operation to remove the coke deposits from the fuel passages. However, this time-maintenance approach, whereby the fuel nozzles are cleaned at regular time intervals, does not accommodate variations in the rate at which a fuel nozzle can get clogged for individual engines. As a result, the fuel nozzles in many engines are often cleaned even though they still operate satisfactorily, in one extreme, or, in the other extreme, at a time well beyond when they became clogged, resulting in possible damage to the engine.
Therefore, it would be highly desirable to have an on-going monitoring system and method that could be used to determine when the fuel nozzles of a gas turbine engine need to be cleaned, or otherwise maintained or replaced, thereby providing the operator with more economic maintenance periods, while still protecting against engine part failure due to hot end distress.